Catheters with integrated lumen and methods of their manufacture and use

ABSTRACT

A catheter with at least one integrated lumen and methods of its manufacture and use are provided. A method of manufacture includes: (1) covering a primary mandrel with a first layer, (2) disposing a second layer on the first layer, wherein the second layer has at least one removable secondary mandrel substantially embedded therein, (3) fusing the first layer to the second layer, (4) removing the secondary mandrel from the second layer to form a secondary lumen, and (5) removing the primary mandrel from the first layer to form a primary lumen. The method may further include forming an inflatable balloon at the surface of the second layer where the secondary lumen forms an opening. Also, auxiliary apparatus, such as snare instruments and bundles of optical fibers, may be inserted through the secondary lumen before or during use of the catheter.

BACKGROUND OF THE INVENTION

This invention relates to medical devices and procedures used during therepair, replacement, or supplement of a medical patient's natural bodyorgan structures or tissues. In particular, this invention relates tocatheters with at least one integrated lumen for use in connection withsuch medical procedures and to methods of their manufacture.

Revascularization of the human heart is a good example of a medicalprocedure that involves the repair and supplement of a patient's bodyorgan. Early procedures were known for revascularizing the human heart,but there were several disadvantages to these procedures. The earliestprocedures involved exposing the heart by means of a midline sternotomyand stopping the beating of the heart to facilitate performance of theprocedure. A graft is used to create a new, uninterrupted channelbetween a blood source, such as the aorta, and the occluded coronaryartery or arteries downstream from the arterial occlusion or occlusions.Such a procedure has significant disadvantages, however, because it ishighly invasive and requires general anesthesia. In fact, thesedisadvantages preclude the use of sternotomy procedures on manypatients.

Less invasive procedures were later developed for revascularizing theheart, but these have disadvantages as well. For example, a thoracostomyinvolves surgical creation of ports in the patient's chest to obtainaccess to the thoracic cavity. Specially designed instruments are theninserted through the ports. Thoracostomy bypass procedures are lesstraumatic than sternotomy bypass procedures, but they are still tootraumatic for some patients and may be inadequate when the number ofsurgical bypasses is large. Another procedure, which is known as athoracotomy, revascularizes the human heart by gaining access to thethoracic cavity with incisions between the patient's ribs, but thisprocedure may still be too traumatic for some patients.

Goldsteen et al. U.S. patent application Ser. No. 08/745,618, filed Nov.7, 1996, which is hereby incorporated by reference herein, discloses aless traumatic surgical technique for revascularizing the human heart. Akey aspect of that invention involves the use of catheters that areinserted into a patient's body through relatively remote entry ports,such as a femoral (leg) artery of the patient, a brachial artery of thepatient, or any other suitable entry point. Control of these instrumentsthroughout their use is from a proximal portion that is outside thepatient at all times. In order to minimize the number of entry ports orto perform any of the specialized surgical techniques disclosed therein,a single catheter instrument may include two or more lumens. However, asthe number of lumens increases, conventional manufacturing methods mayyield catheters that have outer diameters that are undesirably large,which may irritate sensitive vessels and preclude their use in narrowvessels. Furthermore, such catheters may be difficult to position andsecure in a patient's body.

In view of the foregoing, it is an object of this invention to provideless traumatic methods and apparatus for revascularizing a patient.

It is another object of the invention to provide methods ofmanufacturing catheters with integrated lumens without substantiallyincreasing the thickness of catheter walls.

It is still another object of the invention to provide a catheter thatcan create a hemodynamic seal when positioned across vessel walls.

It is yet another object of the invention to provide a catheter that canbe positioned in a vessel and used to selectively secure one or moremedical devices therein.

SUMMARY OF THE INVENTION

These and other objects of the invention are accomplished in accordancewith the principles of the invention by providing a catheter having atleast one secondary lumen. The catheter includes a first flexibletubular layer with a primary lumen or passageway inside, and a secondflexible layer that is at least partially fused to the outer surface ofthe first layer. The second layer has at least one secondary lumen thatis substantially integrated into the second layer and opens through thesecond layer at a secondary lumen opening. In a preferred embodimentaccording to this invention, the catheter may further include astructural layer that is located substantially between the first andsecond layers.

A method for making a catheter in accordance with this invention is alsoprovided. In a first step, a primary mandrel is covered with a firstlayer having an outer surface. In a second step, a second layer isdisposed on a portion of the outer surface of the first layer. Thesecond layer substantially forms the catheter wall and has at least oneremovable secondary mandrel substantially embedded therein. In a thirdstep, the first layer is fused to the second layer. In a fourth step,the secondary mandrels are removed from the second layer to formrespective secondary lumens. Each of the secondary lumens opens at asurface of the second layer at a respective secondary lumen opening. Asecondary lumen may extend through the first layer if the secondaryopening is at the radially inner surface of the second layer. And in afifth step, the primary mandrel is removed from the first layer to forma primary lumen.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a longitudinal sectional view of an illustrative catheterwith two integrated lumens in accordance with this invention.

FIG. 1B is a cross sectional view of the illustrative catheter shown inFIG. 1A taken along line 1B--1B.

FIG. 2A is a simplified longitudinal sectional view showing a possiblealternative construction of a secondary lumen in a catheter inaccordance with this invention.

FIG. 2B is a simplified longitudinal sectional view showing anotherpossible alternative construction of a secondary lumen in a catheter inaccordance with this invention.

FIG. 2C is a simplified longitudinal sectional view showing yet anotherpossible alternative construction of a secondary lumen in a catheter inaccordance with this invention.

FIG. 3A is a simplified longitudinal sectional view showing a portion ofan illustrative procedure using a snare instrument and related apparatusin accordance with the invention.

FIG. 3B is a simplified view similar to FIG. 2 showing a later stage inthe illustrative procedure depicted in part by FIG. 3A, together withrelated apparatus, all in accordance with this invention.

FIG. 3C is a simplified view showing the catheter of FIG. 1A passingthrough, and creating a hemodynamic seal at a vessel wall.

FIG. 4 is a flow chart of steps for carrying out an illustrativeembodiment of the procedure for manufacturing a catheter having at leastone integrated lumen according to this invention.

FIG. 5A is a longitudinal sectional view showing an initial stage in theFIG. 4 procedure.

FIG. 5B is a view similar to FIG. 5A showing a later stage in the FIG. 4procedure.

FIG. 5C is a view similar to FIG. 5B showing a still later stage in theFIG. 4 procedure.

FIG. 5D is a view similar to FIG. 5C showing a even later stage in theFIG. 4 procedure.

FIG. 5E is a view similar to FIG. 5D showing a further stage in the FIG.4 procedure.

FIG. 5F is a view similar to FIG. 5E showing a last stage before the endresult, shown in FIG. 1A, of the procedure depicted by FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, a catheter having at least oneintegrated lumen in a catheter wall, and methods for the manufacture anduse of such a catheter, are provided. The method of manufacture involvescovering a primary mandrel with a first layer and fusing a second layer,having at least one integrated lumen, to the outer surface of the firstinner layer. The integrated lumen may be used to position or securemedical devices or to deliver fluids to a particular location anywherealong the catheter's length.

As shown in FIG. 1A, catheter 100 includes at least first flexible layer110 and second flexible layer 130 around longitudinal axis 160. Firstlayer 110 has outer surface 115 and primary lumen 120, which extendslongitudinally inside first layer 110. Second layer 130 has innersurface 135 that is at least partially fused to outer surface 115 offirst layer 110. Second layer 130 has secondary lumens 140 and 150 thatare substantially integrated into second layer 130 and open throughsecond layer 130 at respective secondary lumen openings 142 and 152. Aswill be discussed more fully below, catheter 100 may further includestructural layer 137, such as a metal braid or coil, which issubstantially located between first layer 110 and second layer 130 forproviding some rigidity to catheter 100.

As shown in FIG. 1B, first layer 110 preferably has an elliptical crosssection, most preferably a substantially cylindrical cross section.First layer 110 can be made from any flexible material, such aspolymers. Polymers that may be used to make first layer 110 according tothis invention include polytetrafluoroethylene (such as that sold underthe trademark TEFLON® by E. I. du Pont de Nemours & Company, ofWilmington, Del.), polyetheramide (such as that sold under the trademarkPEBAX®, by Ato Chemie, of Courbeboie, France), polyamide, or polyimide.

The magnitude of inner diameter 121 of first layer 110 depends on theparticular vascular intervention for which catheter 100 is used, but cancertainly range from about 0.050 inches to about 0.225 inches. Firstlayer 110 is preferably thin and has a wall thickness 122 of betweenabout 0.001 inches and about 0.003 inches. Second layer 130 may be anypolymer that is capable of flowing when subject to elevated temperaturesduring fusing, such as polyetheramide, polyamide, or polyimide. Outersurface 115 of first layer 110 is preferably roughened to improveadhesion to inner surface 135 second layer 130. Outer surface 115 may beroughened mechanically or chemically, but any roughening technique maybe used. One type of chemical etching technique involves exposing thesurface to tetrafluoroethylene (such as that sold under the trademarkTETRA-ETCH®, by W. L. Gore & Associates, Inc., of Newark, Del.).

The second layer has at least one substantially integrated secondarylumen. As shown in FIG. 1A, second layer 130 has integrated secondarylumens 140 and 150. According to this invention, any number of secondarylumens could be integrated at nearly any location in second layer 130,depending on the particular vascular intervention. For example, twosecondary lumens 140 and 150 provide fluid communication to inflatableballoons 144 and 154 that can form a hemodynamic seal at a vessel wall.

The locations of integrated lumens also depend on the particularvascular intervention. As best shown in FIG. 1B, catheter 100 has twosecondary lumens 140 and 150 that are preferably substantially adjacentto inner surface 135 of second layer 130 and located on opposite sidesof primary lumen 120. Secondary lumens 140 and 150 are preferablyintegrated near inner surface 135 to improve the strength of, andprevent kinking in, catheter 100. This inner surface arrangement is incontrast to an intermediate arrangement, where the secondary lumen islocated intermediately between inner surface 135 and outer surface 131.That intermediate arrangement divides the wall thickness into twothinner portions which are not as structurally robust as the innersurface arrangement shown in FIGS. 1A and 1B. As shown in FIG. 1A,secondary lumens 140 and 150 also extend substantially parallel tolongitudinal axis 160 for at least a portion of catheter 100.

Although both ends of a secondary lumen are open to provide access tothe secondary lumen, only the distal end of a secondary lumen is shownin the FIGS. That distal opening may be formed at any surface of thesecond layer. For example, FIGS. 2A-2C show catheters having secondarylumen openings on the radial outer surface, distal end, and radial innersurface of a second layer, respectively. In FIG. 2A, catheter 210 hasfirst layer 212, structural layer 214, and second layer 216. Secondlayer 216 of catheter 210 has one secondary lumen 218, which has outersecondary lumen opening 219 at outer surface 215 of second layer 216. InFIG. 2B, catheter 220 has first layer 222, structural layer 224, andsecond layer 226. Second layer 226 of catheter 220 has one secondarylumen 228, which has distal secondary lumen opening 229 at distal end225 of second layer 226. Finally, in FIG. 2C, catheter 230 has firstlayer 232, structural layer 234, and second layer 236. In catheter 230,second layer 236 has one secondary lumen 238, which has inner secondarylumen opening 239 at inner surface 235 of second layer 236. Catheter 230also preferably has secondary lumen extension 240, which extends throughfirst layer 232. Extension 240 extends from secondary lumen opening 239to extension opening 249 located on inner surface 233 of first layer232. In order to provide fluid communication between secondary lumen 238and extension 240, structural layer 234, which acts like a flexibleskeleton, is preferably porous. Structural layer 234, for example, maybe made from any relatively stiff structural material, such as stainlesssteel braid or coil.

As shown in FIG. 1, catheter 100 may further include one or moreinflatable balloons 144 and 154. These balloons are formed at respectivesecondary lumen openings 142 and 152 by covering the openings withelastic sheets or tubes, preferably bonded to outer surface 131 ofsecond layer 130. Balloons 144 and 154 may also be formed from a singleelastic sheet that covers both openings. In that case, a continuousstrip of the sheet may be bonded to outer surface 131 of second layer130 between openings 142 and 152 to form two separate compartments thatare separately inflatable and deflatable. On the other hand, theballoons may be in fluid communication with each other so that only onesecondary lumen is required to inflate or deflate, but the balloons inthis case would not be independently controllable. Fluid communicationbetween the balloons can be obtained by only partially bonding the stripof the sheet between the balloons. When two balloons are formed adjacenteach other for gripping a vascular wall, as shown in FIGS. 1A and 3C,proximal secondary lumen opening 142 and distal secondary lumen opening152 preferably have an axial separation that is greater than a thicknessof the vascular wall. Because secondary lumens 140 and 150 extendoutside of a patient during catheter use, the fluid pressure in theballoons can be monitored at the proximal end of the secondary lumen andcontrolled as desired.

The elastic sheets used to form balloons 154 and 154 may be bonded toouter surface 131 of second layer 130 by adhesive or heat treatment. Theelastic sheet or tube may be made from any flexible material, such aspolyurethane, silicone, rubber, and preferably latex materials (such asthat products sold by The Pioneer Rubber Company, of Willard, Ohio or byCalifornia Latex Inc., of Pomona, Calif.). Preferably, the modulus ofthe elastic sheet or tube is between about 200 and about 2,500 psi. Theouter surface of the balloon may be provided with channels to facilitatefluid flow when the balloon is inflated in a vessel. When the sheet hasan annular shape that fits circumferentially around second layer 130,the sheet may be bonded to outer surface 131 along the sheet edges ortube ends to form an annular balloon. The elastic sheet or tube may bepreformed before being bonded to outer surface 131 so that the sheetforms a hollow ring that opens radially inward. Preferably, the radiallyouter portion of the ring is larger than the radially inner portion ofthe ring so that a cross-section of the ring has a bulbous shape.

FIG. 3C shows catheter 370 (which is similar to catheter 100) secured tovascular wall 380 with a hemodynamic seal. Securing is preferablyaccomplished by at least partially inflating proximal balloon 374,inserting distal end 371 of catheter 370 through vascular wall 380 untilwall 380 presses against inflated proximal balloon 374, and inflatingdistal balloon 372. Inflation of distal balloon 372 secures vascularwall 380 between balloons 372 and 374 and forms a hemodynamic sealbetween wall 380 and balloons 372 and 374. Although preinflation ofproximal balloon 374 may be preferable to avoid over-insertion ofcatheter 370, both balloons may be deflated during the inserting stepand inflated after the inserting step.

In addition to providing fluid communication to balloons, the secondarylumens may be used to position or secure the catheter itself or otherauxiliary medical apparatus, or to deliver fluids to a particularlocation along the catheter's length.

One such medical apparatus is endoscopic snare instrument 350 (see FIG.3A). Instrument 350 includes shaft 352 with snare loop 354 at its distalend. Loop 354 is substantially closed when it is inside a snare sheath(not shown) or secondary lumen 340. Loop 354 may open resiliently to theshape shown in FIG. 3A when extended distally through secondary lumenopening 356 or when extended distally through secondary lumen opening366 beyond distal end 360 of a sheath or secondary lumen 340.

During operation, snare loop 354 may initially be in an open position inprimary lumen 320 for subsequent securing of device 390 within primarylumen 320. In this case, inner surface 310 of catheter wall 305 may haverecessed portion 307 for receiving open snare loop 354 so that loop 354does not catch on device 390 when it is inserted through primary lumen320. Once device 390 is inserted, loop 354 may be retracted intosecondary lumen 340, as shown in FIG. 3B. In that case, snare loop 354contracts and secures any guide wire, safety wire, or any other medialdevice 390 inside loop 354. As shown in FIG. 3A, a snare may be also bepositioned at distal end 360 of catheter 300 for holding, snaring, orretrieving.

An advantage of using a snare instrument in a secondary lumen is thatthe principal catheter function (such as the installation of a newlength of graft in a patient) and the secondary snare function (such asthe securing of a device) may be performed simultaneously, eliminatingthe need to exchange one catheter for another during an operation.

The secondary lumen may guide, in addition to snare instruments, otherauxiliary apparatus. For example, a secondary lumen may guide a fiberoptic bundle for transmitting light to the vascular site or fortransmitting an image of the vascular site to the doctor performing theoperation. A single bundle of fibers may also perform both functions.

As described above, catheter 100 may include structural layer 137, suchas a metal braid or coil. Structural layer 137 is located substantiallybetween first layer 110 and second layer 130 for providing mechanicalrigidity to catheter 100. As explained more fully below, the manufactureof catheter 100 involves fusing first layer 110 to second layer 130. Inorder to ensure proper bonding, structural layer 137 must not completelyseparate first layer 110 and second layer 130. Therefore, any porousstructure that provides contact between first layer 110 and second layer130, such as metal braid or coil, would be an appropriate structuralmaterial. Structural layer 137 may also be embedded directly in secondlayer 130 before bonding first layer 110 to second layer 130.

FIG. 4 shows an illustrative sequence of steps in accordance with thisinvention for manufacturing a catheter with at least one integratedlumen, such as catheter 100 shown in FIG. 1. These steps are describedbelow with reference to FIGS. 5A-5F, which show catheter 100 at variousintermediate manufacturing steps. To some extent these steps havealready been mentioned, so the discussion of them here may be somewhatabbreviated.

A method in accordance with this invention for making a catheter withintegrated lumens involves covering a primary mandrel with a first layerand fusing a second layer, which has at least one integrated lumen, tothe outer surface of the first layer. The exact number and location ofthe secondary lumens is a matter of design.

In particular, primary mandrel 50 is covered with first layer 110 instep 410 (see FIG. 5A). In step 414, an optional structural layer 137may be placed over first layer 110 (see FIG. 5B). Then, in step 420,second layer 130 is disposed over outer surface 115 of first layer 110and optional structural layer 137 (see FIG. 5C). Second layer 130 has atleast one secondary mandrel, which is preferably substantially embeddedin second layer 130. FIG. 5C shows second layer 130 with embeddedsecondary mandrels 132 and 133. Next, in step 430, first layer 110 isfused to second layer 130 (FIG. 5D). In step 440, secondary mandrels 132and 133 are removed from second layer 130 to form secondary lumens 140and 150, each of which opens through second layer 130 at respectivesecondary lumen openings 142 and 152 (FIG. 5E). In step 445, balloons144 and 154 may be formed at respective secondary lumen openings 142 and152 (FIG. 5F). And, in step 450, primary mandrel 50 is removed fromfirst layer 110 to form primary lumen 120 (e.g., FIG. 1A). As always,the number, positions, and sizes of the integrated secondary mandrelsdepend on the particular vascular operation being performed.

Also, primary mandrel 50, which forms inner surface 111 of first layer110, can have any cross sectional shape, but preferably has a generallyelliptical shape. Most preferably, it has a circular cross section(e.g., FIG. 1B). These shapes are desirable because they have no sharpcorners or edges that may snag or cause friction in primary lumen 120during operation. Primary mandrel 50 is preferably made of a materialcapable of withstanding high temperatures and pressures, such as steel,and preferably stainless steel, because fusing step 430 may involve suchconditions. Outer diameter 121 of primary mandrel 50 is preferablybetween about 0.050 inches and about 0.225 inches. For many vascularapplications, outer diameter 121 of mandrel 50 (or equivalently innerdiameter 121 of first layer 110) can be about 0.160 inches.

First layer 110, which covers primary mandrel 50, may be made from anyflexible material, such as many commonly available polymers.Polytetrafluoroethylene is a preferred flexible material. Because onefunction of first layer 110 is to provide a relatively low frictioninternal surface 111 for passing devices in primary lumen 120, the outersurface of primary mandrel 50, which may be used to mold inner surface111, is preferably smooth. Wall thickness 122 of first layer may bebetween about 0.001 inches and about 0.003 inches. First layer 110 maybe deposited onto primary mandrel 50 from a vapor or formed by sliding afirst tubular layer over primary mandrel 50.

Unlike inner surface 111, outer surface 115 is preferably rough tofacilitate fusion to inner surface 135 of second layer 130. Therefore,outer surface 115 is preferably roughened in step 412 before fusing step430 so that surfaces 115 and 135 can fuse properly. Roughening may beaccomplished by mechanically or chemically etching outer surface 115,such as by treatment with tetrafluoroethylene, or molding or extrudingfirst layer 110 so that outer surface 115 is initially rough.

In step 414, structural layer 137 may be inserted over first layer 110before disposing step 420, or inserted as an integrated (or embedded)portion of second layer 130 during step 420. If first layer 110 iscovered with structural layer 137 in step 414, structural layer 137should only partially cover first layer 110 so that first layer 110 andsecond layer 130 are at least partially in contact with each other forfusing in step 430. In this way, structural layer 137 is substantiallybetween first layer 110 and second layer 130. Structural layer 137 maybe any material that prevents primary lumen from collapsing, yetprovides a flexible skeleton that allows catheter 100 to bend asrequired, such as stainless steel in the form of a braid or coil, forexample.

In step 420, after primary mandrel 50 is covered with first layer 110(and optionally structural layer 137), second layer 130 is disposed onat least a portion of outer surface 111 of first layer 110. Second layer130 has at least one secondary mandrel (e.g., mandrels 132 and 133)substantially embedded therein. The secondary mandrels may be placedbetween first layer 110 and second layer 130 and substantially embeddedinto second layer 130 during fusing in step 430. Disposing step 320 mayinclude sliding a hollow tube over first layer 110 until the tubesubstantially covers that layer. The tube, which becomes second layer130, may be preformed during extrusion or molding so that the tubecontains at least one integrated secondary lumen with a removablesecondary mandrel. Although a secondary mandrel helps prevent thesecondary lumen from collapsing during fusing step 430, in some casesthe secondary mandrel may be removed before fusing. The tube that formssecond layer 130 may also be preformed with an integrated lumen butwithout a secondary mandrel. In that case, the secondary mandrel may beembedded into the secondary lumen before fusing step 430.

As described above, secondary lumens 140 and 150 may be integratedanywhere in second layer 130. For example, secondary lumens may beintegrated substantially adjacent to inner surface 135 (as shown in FIG.1B) or outer surface 131 of second layer or tube 130. Secondary lumens140 and 150 preferably extend longitudinally for at least a portion ofcatheter 100, but may extend radially (or any direction therebetween)for another portion, as shown near lumen openings 142 and 152. In orderto ensure that catheter 100 will not collapse or break during use,minimum thickness 132 of second layer 130 is preferably at least about0.003 inches along a substantial length of the secondary lumens. Also,as already described above, secondary lumen openings 142 and 152 may beformed at outer surface 131 (FIGS. 1A and 2A), inner surface 135 (FIG.2C), or distal end 125 of the tube forming second layer 130 (FIG. 2B).As shown in FIGS. 3A and 3B, a single lumen may also have more than oneopening.

In fusing step 430, outer surface 115 of first layer 110 is fused toinner surface 135 of second layer 130. As shown in FIG. 5D, this may beaccomplished in a series of sub-steps. In one series of sub-steps, heatshrink tubing 162 is placed over second layer 130 in step 431 and heatedso that it applies a radially inward force against outer surface 131 ofsecond layer 130 in step 433. The force, in combination with heat,causes first layer 110 to at least partially fuse to second layer 130.Typical fusing temperatures range from about 300° F. to about 600° F.Preferably, the fusing temperature is about 450° F. After heating step433, heat shrink tubing 162 is preferably removed in step 435.

In an alternate series of sub-steps, fusing may be accomplished byextruding second layer 130 on first layer 110 in step 432 and embeddingsecondary mandrel 132 and 133 in second layer 130 during extruding instep 434. Then, in step 436, heat is preferably applied to second layer130 so that first layer 110 fuses to second layer 130. Fusing step 430may always include applying heat to first layer 110 by heating primarymandrel 50 as well.

In step 445, after fusing in step 430, one or more inflatable balloons144 and 154 may be formed at integrated secondary lumen openings 142 and152 by bonding one or more elastic sheets or tubes around thoseopenings. The elastic sheets may be formed from any elastic material,such as polyurethane, silicone, rubber, or latex-based materials andbonded to second layer 130 by applying sufficient heat and/or adhesive(preferred) to a portion of the sheet to cause that portion to partiallymelt. When the melted portion cools, it forms a fluid, or hemodynamic,seal about the opening so that balloons 144 and 154, which are formedinside the seal, can be inflated and deflated with a fluid, such as agas or liquid. Alternatively, the elastic sheet may be bonded to asurface of second layer 130 by applying an adhesive material to aportion of the sheet bonded to second layer 130. This works particularlywell when the elastic sheet is a silicone, rubber, or latex material. Asalready described above, the elastic sheet can have any shape, includingany preformed shape, as long as it completely covers integrated lumenopenings 142 and 152 and has borders 145 and 155 sufficient for bonding.

In steps 440 and 450, the primary and secondary lumens are formed byremoving the primary and secondary mandrels, respectively. For example,in step 450, primary lumen 120 is formed by removing primary mandrel 50from inside first layer 110. Also, in step 440, secondary lumens 140 and150 are formed by removing secondary mandrels 132 and 133 from secondlayer 130. Steps 440 and 450 may be performed in any order and before,during, or after balloons 144 and 154 are formed in bonding step 445.However, it is preferable that at least step 445 is performed beforestep 450 so that primary mandrel 50 provides structural support duringstep 445.

In step 460, one or more auxiliary apparatus may be inserted in thesecondary lumen. Examples of auxiliary apparatus include endoscopicsnare instruments (as shown in FIGS. 3A and 3B) and fiber optic bundles.In the case of a snare instrument, inserting step 460 may involveinserting the instrument so that snare loop 354 of instrument 350 isnear the secondary lumen opening 356. When snare instrument 350 includesa snare sheath, method 400 may further include inserting the sheath insecondary lumen 340 before or during inserting step 360, in which snareinstrument 350 is itself inserted so that the snare loop remains fullyopen when placed in the primary lumen. The snare loop may be preformedbefore being inserted. When the auxiliary apparatus includes a fiberoptic bundle that has a tip portion, the tip portion may be positionednear a secondary lumen opening (see FIG. 3A).

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. For example, the order of some steps in the proceduresthat have been described are not critical and can be changed if desired.

The invention claimed is:
 1. A method for making a catheter with atleast one integrated secondary lumen, said method comprising:covering aprimary mandrel with a first layer having an outer surface; disposing asecond layer on at least a portion of said outer surface of said firstlayer, said second layer and having at least one removable secondarymandrel substantially embedded therein; fusing said first layer to saidsecond layer; removing said at least one secondary mandrel from saidsecond layer to form at least one secondary lumen, wherein each of saidsecondary lumens opens through said second layer at a respectivesecondary lumen opening; and removing said primary mandrel from saidfirst layer to form a primary lumen.
 2. The method of claim 1 whereinsaid covering comprises covering a primary mandrel that has an outerdiameter of between about 0.050 inches and about 0.225 inches.
 3. Themethod of claim 1 wherein said covering comprises covering a primarymandrel that has an outer diameter of about 0.160 inches.
 4. The methodof claim 1 wherein said covering comprises covering with a first layerthat comprises a polymer.
 5. The method of claim 4 wherein said coveringcomprises covering with a polymer consisting of polytetrafluoroethylene,polyamide, polyimide, or polyetheramide.
 6. The method of claim 4wherein said covering comprises covering with a first layer having athickness of between about 0.001 inches and about 0.003 inches.
 7. Themethod of claim 4 wherein said covering comprises depositing bycondensation of vapor.
 8. The method of claim 4 wherein said coveringcomprises sliding said first layer onto said primary mandrel.
 9. Themethod of claim 8 further comprising roughening an outer surface of saidfirst layer to improve said fusing.
 10. The method of claim 9 whereinsaid roughening comprises mechanically or chemically etching said outersurface of said first layer.
 11. The method of claim 1 wherein saiddisposing comprises sliding a hollow tube over said first layer untilsaid tube substantially covers said first layer, said tube forming saidsecond layer.
 12. The method of claim 11 further comprising extrudingsaid tube with at least one passageway for embedding a respective saidat least one secondary mandrel.
 13. The method of claim 12 furthercomprising embedding said at least one secondary mandrel into saidrespective at least one passageway.
 14. The method of claim 12 whereinsaid disposing comprises disposing a tube with a passagewaysubstantially adjacent a radially inner surface of said tube.
 15. Themethod of claim 12 wherein said disposing comprises disposing a tubewith a substantially longitudinal passageway.
 16. The method of claim 15wherein said disposing comprises disposing a tube with a substantiallylongitudinal passageway and a minimum catheter wall thickness of about0.003 inches along a substantial length of said passageway.
 17. Themethod of claim 12 wherein said disposing comprises disposing a tubewith a passageway that opens on an outer surface of said tube to form anouter secondary lumen opening.
 18. The method of claim 12 wherein saiddisposing comprises disposing a tube with a passageway that opens on aninner surface of said tube to form an inner secondary lumen opening. 19.The method of claim 12 wherein said disposing comprises disposing a tubewith a passageway that opens at a distal end of said tube to form a tipsecondary lumen opening.
 20. The method of claim 1 wherein said fusingcomprises:placing heat shrink tubing over said second layer, said heatshrink tubing having an inner diameter; heating said heat shrink tubingso that said inner diameter decreases, thereby causing said second layerto apply a radially inward force to said first layer so that said layersat least partially fuse to each other; and removing said heat shrinktubing after said heating.
 21. The method of claim 1 wherein saiddisposing a second layer comprises:extruding said second layer on saidfirst layer; and substantially embedded said at least one secondarymandrel in said second layer during said extruding; and wherein saidfusing comprises: applying heat to at least said second layer so thatsaid first layer fuses to said second layer.
 22. The method of claim 1wherein said fusing comprises applying heat to said first layer byheating said primary mandrel.
 23. The method of claim 1 furthercomprising bonding an elastic sheet around said secondary lumen openingto form an inflatable balloon.
 24. The method of claim 23 wherein saidbonding comprises applying heat to a portion of said sheet.
 25. Themethod of claim 24 wherein said sheet comprises polyurethane.
 26. Themethod of claim 23 wherein said bonding comprises applying an adhesivematerial to a portion of said sheet where said sheet is bonded to saidsecondary lumen.
 27. The method of claim 26 wherein said sheet comprisessilicone.
 28. The method of claim 27 wherein said sheet comprisespolyurethane.
 29. The method of claim 23 wherein said elastic sheet isannular and has a first axial end and a second axial end, said bondingcomprising bonding said axial ends to said second layer to form anannular balloon that covers said secondary lumen opening.
 30. The methodof claim 1 further comprising inserting an auxiliary apparatus in atleast said secondary lumen.
 31. The method of claim 30 wherein saidauxiliary apparatus includes an endoscopic snare instrument having asnare loop, and wherein said inserting comprises inserting said snare insaid lumen so that said snare loop is near said secondary lumen opening.32. The method of claim 31 wherein said snare instrument furthercomprises a snare sheath, and wherein said inserting further comprisesinserting said sheath in said secondary lumen.
 33. The method of claim30 wherein said auxiliary apparatus includes a fiber optic bundle havinga tip portion, and wherein said inserting comprises inserting saidbundle in said lumen so that said tip portion is near said secondarylumen opening.
 34. The method of claim 1 further comprising coveringsaid first layer with a structural layer before said disposing of saidsecond layer, so that said structural layer is between said first andsecond layers.
 35. The method of claim 34 wherein said covering with astructural layer comprises covering said first layer with braided metal.36. The method of claim 34 wherein said covering with a structural layercomprises covering said first layer with a metal coil.
 37. The method ofclaim 1 wherein said covering comprises covering a primary mandrel thatcomprises a material capable of withstanding high temperatures andpressures during said fusing.